Telegraph system



Dec. 31, 1946. R. s. HEWITT TELEGRAPH SYSTEM Filed Jan. 25, 1944 gala INV'ENTOR. .Roland S. f/8wlfii' Patented Dec. 31, 1946 UNITED STATES PATENT OFFICE.

TELEGRAPH SYSTEM Roland S. Hewitt, Osawatomie, Kans.

Application January 25, 1944, Serial No. 519,668

2 Claims. (Cl. 178-41) This invention appertains to telegraph systems generally, and more particularly to an improved system of control for the operation of teletype machines.

An object of the invention is to provide a system of this character that is simplified into a single line of double control of teletype machines and wherein absolute control of the operations of the machines is effected from each end of the line and no current is consumed in any part of the system when the printer mechanisms of the machines are idle.

Another object of the invention has to do with the provision of a system of this kind and one which obviates the need for employment of a second or return power line by the grounding of either the positive or negative sides, depending upon the polarity required, thus economizing in current consumption by the elimination of resistance otherwise present in the system andreducing the cost of line construction and expense of operation.

With these and other objects and advantages of equal importance in view, the invention resides in the certain new and useful combination, construction and arrangement of instrumentalities, parts and circuits, as will be hereinafter more fully described, set forth in the appended claims, and illustrated in the accompanying drawing, in which the figure is a diagrammatical view of a two station teletype system, in accordance with the invention.

The system, as illustrated, is comprised in a line wire II extending between two stations A and B and has its ends in electrical connection with the operative mechanisms l2 of teletype machines, such as the printer mechanisms thereof, each of which includes a motor M. The station A is provided with a transmitter C and the station B with a transmitter D.

Cooperative with the operative mechanism l2 at the station A is a relay l3 that is provided with a pair of flexible contacts [4 and I 5, and has the contact l4 electrically connected by a lead IE to one terminal of the motor M and the contact l5 to a motor circuit lead l'l', while the remaining terminal of the motor M is connected to the other motor circuit lead l8.

The station A also includes a toggle line switch that has contacts l9 and 20 selectively engageable by a pivoted switch lever 2| for their respective movements into electrical engagement with station contacts 22 and 23. A positive line wire 24 is electrically connected to the station contact 22, while the station contact 23 is electrically connected by a lead 25 to a negative ground. A voltage source, such as a battery V, is connected across the leads 24 and 25, substantially as shown in the drawing. The polarity of these power line connections 24 and 25 may be reversed, if required. Both of the contacts l9 and 29 are electrically connected by a common lead 26 to one of the terminals of the relay I3, which has its other terminal electrically connected by a lead 21 to the operative mechanism l2 of station A.

Likewise, station B has a relay 28 that is cooperative with the operative mechanism I2 and it is provided with a pair of flexible contacts 29 and 30, with the contact 29 electrically connected by a lead 3| to one terminal of the motor M and the contact 30 to a motor circuit lead 32, while the remaining terminal of the motor M is connected to the other motor circuit lead 33.

Station B also includes a toggle line switch that has contacts 34 and 35 selectively engageable by a pivoted switch lever 36 for their respective movements into electrical engagement with station contacts 31 and 38, the station contact 31 being in electrical connection with a lead 39 to a negative ground and the station contact 38 with a positive power line wire 40. Here, a voltage source, such as a battery V, is connected across the leads 39 and 40. Both of the contacts 34 and 35 are electrically connected by a common lead 4| to one of the terminals of the relay 28 which has its other terminal electrically connected by a lead 42 to the operative mechanism l2 of station B.

In the operation of the system as illustrated, and with the switch lever 2|, of the toggle switch at station A, positioned to engage the contact '20 with the station contact 23 and the switch lever, of the toggle switch at station B, to engage the contact 35 with the station contact 38, current will flow by way of the contacts 38 and 35 and the lead 4| to the relay [3 at station B. With current flow, the relay 28 will be energized and closes its contacts 29 and 30, on the local power supply 32 and 33 of the motor M of the operative mechanism or printer l2. From the relay 28, the current passes through the operative mechanism or printer 12 to the line wire ll and from thence through the operative mechanism or printer l2 to the relay [3 at station A. With the energization of relay [3, its contacts l4 and I 5 are closed on the local power circuit l1 and N3 of the motor M of the operative mechanism or printer I2. From the relay l3, the current flows by way of lead 26 to the contacts 20 and 23 of the toggle switch at station A and from thence 3 by way of the lead 25 to ground. Under these conditions, both teletype machines at the stations A and B are placed in operation.

If now an operator at one of the stations, for instance, the station A, moves the switch lever 2| to open the circuit at the contacts 20 and- 23 and to close it at the contacts I9 and 22, the machines at both of the stations A and B will be stopped by the absence of current ,fiow. throughout the system and the consequent ie-energizing of the relays I3 and 23 to open the power circuits 'on the motors M. If upon returning the circuit of the system at the toggle switch at station A in the manner stated, the operator at this station has need to transmit a message to station B, he will move the switch lever 21 back to its first position to again close the circuit at thecontacts 20 and 23, or with the switch lever 2| set at its second position to close .the contacts l9 and 22, the operator at station B may transmit a message to station A by moving the switch lever, of the toggle switch at station B, to open the circuit at the contacts 35 and 38, and to close it at :the contacts 34 and 37, when current flow will be restored to the system. Thus, either operator may start or stop both of the teletype machines.

The motor control relays l3 and 28 are preferably of a design to provide a delayed action with respect to the opening of the power circuits of the motors M at their respective pairs of contacts l4 and I5, and 2,9 and 30, such a relay constituting the subject-matter of my co-pending application, filed March 31, 1942, and serially numbered 437,098.

In the transmission of signals, the printer signals are passed over the line H at a rapid rate, the operation being characterized by current and no-current impulses, i. e., periods when the line is opened and closed. Each current impulse causes a rapid closing of the contact pairs l4-l5 and 29-40 of the relays l3 and 28, while each no-current impulse causes the relays to retard the opening movement of the contacts and, since the printer signals are passed quickly, the contacts are maintained in closed position with respect to the action of the current and no-current impulses. No time limit is involved in the closing of the contacts but there is a time limit involved in the opening of the contacts, which is brought about by the fact that the contacts are closed and flexed beyond their initial contacting positions so that the contacts must move a considerable distance in the return direction before they are electrically disengaged one from the other. In addition, the spring tension of the contacts is opposed in a manner to delay the opening of the same until another closed signal causes the relays to move the contacts beyond their initially engaging positions. Consequently, when a stop period is required, the tension of the contacts completely overcomes the opposition and allows them to separate.

The switches 2| and 36 each remains closed at all times, engaging either the positive or negative ,contact. The operator of a given switch may control the circuit by adjusting his switch to the potential of the other switch for stopping the printers [2 by adjusting the switches to the same potential at both stations. To start the current flowing, one of the two stations must have its switch adjusted to the opposite potential.

, Without further elaboration, the foregoing will so fully illustrate my invention, that others may, by applying current knowledge, readily adapt the same for use under various conditions of service.

What I claim is: v

1. In a printing-telegraph system, sending-receiving stations, a line circuit interconnecting said stations, means for controlling starting and stopping operations of a receiving station from a sending station, a voltage source for each of said stations, and a manually operable switch at each station for selectively reversing the polarity of current applied to said line circuit from said voltage sources to control the operation of said means.

2. A printing-telegraph system, comprising a plurality of sending-receiving stations, a line circuit interconnecting said stations, a relay at each station for controlling starting and stopping operations of a receiving station from a sending station, a voltage source for each of said stations, means including a three point switch at each station for selectively reversing the polarity of current applied to said line circuit from said voltage sources to control the operation of said relays, said relays having a time delay action in effecting said stopping operations.

ROLAND S. HEWITT. 

